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Lecture 11 Thursday 2/7/08. Determining the Rate Law from Experimental Data Integral Method Graphical Method Nonlinear Least Regression Multiple Reactions The Four Types What’s New to Our Algorithm Reactions in Series. Levenspiel Plot.
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Lecture 11 Thursday 2/7/08 Determining the Rate Law from Experimental Data Integral Method Graphical Method Nonlinear Least Regression Multiple Reactions The Four Types What’s New to Our Algorithm Reactions in Series
Two steps to get Step 1: Rate Law Step 2: Stoichiometry Step 3: Combine to get
Finding Rate Laws, Multiple Reactions ln Slope = α dCA/dt ln CA Areas equal for both sides of the histogram .3 .2 .1 t Find the f(t) of using equal area differentiation 1 2 3 ln dCA/dt Slope = α Plot –dCA/dt as a function of CA α = slope CA
Regression Method Guess values for α and k and solve for measured data points then sum squared differences for α = 2, k = 1 → S2 = 0.079 for α = 2, k = 2 → S2 = 0.27 etc. until S2 is a minimum
4 Types of Multiple Reactions • Series: A → B → C • Parallel: A → D, A → U • Independent: A → B, C → D • Complex: A + B →C + D, A + C → E • With multiple reactors, either molar flow or number of moles must be used (no conversion!) • FlowBatch • Rates: rate law for each reaction • net rates: • the sum of rates for each reaction given
example: 1) A + B → C + D -r1A= k1ACACB-r2A= k1ACACC 2) A + B → E etc…. relative rates: only applied to a given reaction Stoich: example: A → B → C (1) A → B k1 (2) B → C k2 1) mole balance: 2) rates: laws net rates V=V0 (constant batch)